Fuel may be supplied to a cylinder of diesel engine during an engine cycle via one or more fuel injection pulses. A first group of fuel injections provided to an engine cylinder during a cycle of the cylinder may be referred to as pilot fuel injections. The pilot fuel injections may be followed by a main injection. The main injection may be followed during the same cylinder cycle via post injections. The pilot fuel injections may be useful to reduce engine noise while the main fuel injection has a purpose of generating engine torque. Post fuel injections may be provided to the engine to deliver thermal energy to emission control devices in the engine's exhaust system or to provide reductants to the emission control devices. Variation in fuel flow for different fuel injectors of the same type may be pronounced at smaller fuel pulse widths where fuel injectors provide pilot fuel injections. Therefore, it may be desirable to periodically update fuel injector transfer functions in a fuel pulse width region or range where the pilot fuel injections are provided. However, it may be difficult to determine fuel injector transfer function errors when an engine is operated with short duration pilot fuel injections. Consequently, it may be difficult to accurately update the fuel injector transfer function when the engine is operated with short duration pilot fuel injections.
The inventors herein have recognized the above-mentioned disadvantages and have developed an engine operating method, comprising: receiving sensor data to a controller; judging if conditions are present for adjusting a fuel injector transfer function via the controller based on the sensor data; and activating a glow plug via the controller in response to the conditions being present.
By selectively operating glow plugs in response to a request to adapt a fuel injector transfer function, it may be possible to provide the technical result of improving fuel injector transfer function adaptation. For example, one or more engine glow plugs may be activated so as to provide more stable and repeatable combustion in engine cylinders during adapting of fuel injector transfer functions. The activated glow plugs may heat engine cylinders to improve combustion stability, thereby providing more uniform engine torque production and engine air-fuel ratio.
The present description may provide several advantages. Specifically, the approach may improve adaptation of fuel injector transfer functions. In addition, the approach may improve engine emissions and combustion stability via providing fuel to the engine more accurately. Further, the approach may reduce engine emissions and noise.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.